The present invention relates generally to mechanisms for opening and closing photographic film packages. In particular, the present invention is a mechanism for opening and resealing film cartridges loaded in a laser imager.
X-ray and other types of medical imaging photographic film are packaged in photo-opaque (i.e., light-tight) containers. Examples of such film packages are disclosed in the Wilcox U.S. Pat. No. 330,182, the Jones et al. U.S. Pat. No. 1,536,345 and the 1958 U.S. Naval Medical School publication entitled "Fundamentals of X-ray Physics & Technique". Medical imaging film commercially available from the 3M Company of St. Paul Minn., the assignee of the present invention, is packaged in laminated metal foil and polymer sheet bags. The film is usually removed from these containers and loaded into the x-ray machines or other medical imagers under darkroom conditions. This procedure is inconvenient and time consuming.
The Schmuck U.S. Pat. No. 1,098,844 and International Application No. PCT/EP88/00166 disclose film packages which can be loaded directly into a camera or other imaging device, thereby alleviating the need for a darkroom. However, the Schmuck film package is a relatively inefficient design and requires manual manipulation to bring the film into exposure position. The Schmuck package is therefore incompatible with the automatic film handling mechanisms typically used in modern imaging systems. The cassette shown in the International Application apparently holds only one sheet of film, necessitating inconvenient and time consuming reloading procedures for each use.
The Tajima et al. U.S. Pat. No. 4,727,391 discloses a package for sheet film and a loading device for the package. The package includes a tray and a flexible cover peelably attached to the tray by an adhesive. The package is loaded into the loading mechanism with the distal end of the cover extending from the mechanism in a light shielding condition between a roller and closure member. The distal end of the cover is gripped and manually pulled to open the package.
Commonly assigned U.S. patent application Ser. No. 07/656,610 entitled "Resealable Film Cartridge For A Laser Imager", which was filed on even date herewith, discloses a film cartridge for multiple sheets of film which is capable of being resealed after it has been opened. The cartridge is configured to be conveniently loaded directly into an imager under daylight conditions. Since it is sometimes necessary to load an imager with a different type or size of film before all the film already in the imager has been used, the cartridge can be resealed and conveniently removed from the imager under daylight conditions without wasting any remaining film.
Use of the resealable cartridge disclosed in the above identified patent application requires a mechanism which can open and reseal the cartridge within the imager. The mechanism must be capable of reliably performing the opening and closing functions. To be commercially viable it must also be capable of being efficiently manufactured.